Design Of Analog Front-end For 3-D Laser Imaging Readout Circuit

In recent years,lasers have been widely used in many fields such as laser measurement,agriculture,communication and storage,modern education,physics research,industrial applications,medical applications and military department.Laser Detection and Ranging(LADAR)is used in military vehicles and aircraft and countries pay more and more attention to it.As a main branch of LADAR technology,3-D laser imaging technology has also been widely used in civil and military applications.Compared with traditional 2-D remote sensing image technology,3-D laser imaging technology can reflect the characteristics of target objects more accurately.However,3-D laser imaging system is mainly limited by the small pixel resolution and slow readout frame rate.To solve these problems,corresponding solutions have been proposed in this paper.This paper designs an analog front-end circuit for 3-D laser imaging readout circuit based on avalanche photodiode(APD).Firstly,according to the analysis and discussion of various methods of laser ranging and the characteristics of the environment and target,the overall proposal of 3-D laser imaging based on the time-of-flight method was determined.Then,a shunt-shunt negative feedback transimpedance amplifier(TIA)for 3-D laser imaging readout circuit is designed.A feedback capacitor is added to improve the stability of the TIA and also reduce the difficulty of the design and the power consumption of the circuit.And we draw the layout,tapeout the TIA chip and finish the test work of the TIA.The measured rise time of the TIA is 3.37 ns,the bandwidth is 89.04 MHz,and the rms output noise voltage is 7.54 mV.Secondly,a peak value detection circuit is designed to detect the intensity of laser pulse.Through the front-simulation of the pixel of the 3-D laser imaging array,the function of detecting the strength of the pulse signal is verified.Based on the design of the TIA and the peak value detection circuit,a 40�2 3-D laser imaging array was proposed and through the simulation of the whole circuit assisted with the digital logic circuit,the possibility of readout of the 3-D laser imaging array was verified.Thirdly,a capless TIA was proposed on the basis of traditional resistive TIA.The performance and layout area of this TIA was designed and optimized.The gain of the TIA is 177k?,and the-3d B bandwidth is 146.77 MHz,the rise time is 4.06 ns,and the rms output noise voltage is 1.895 mV.Finally,a pixel circuit and a 64�64 laser 3-D imaging readout circuit array are designed based on the capless TIA.The layout of the capless TIA,the pixel circuit and the 64�64 laser 3-D imaging readout circuit array were also drawn and taped out.